i!
882
Appendix II.
by re-heaters, the only reason for whose success lies in the remark-
able economy of heat thus supplied, some six times as efficiently
as when used in a steam boiler.
P. 605-8. Plotting the Curve pVn = C,—The pressure
for given volume, or volume for given pressure, can be found by
using a table of logarithms, for
Note that ~~1
common logs. I
are used. J
log/ -f fllogV — log C
log/ = logC - «logV
, . ,r JosjC-log/
and logV = & to/
n
The values / or V may then^be deduced, being the numbers
corresponding to their logarithms. Or, again, the values n and C
for a given curve, may be found by construction. Taking the
given expansion curve, Fig. 842, measure every pressure and
FMf.842.
— J -
volume at any points i, 2, 3, 4, 5, arid, on a new diagram, shewn
below, plot their logarithms, drawing the best straight line A B
through the plotting. Then
AC
C"B
and log/ 4- — logV = logC
C B
Putting in the values for log/ and log V, taken anywhere, log C